1. Field of Invention
The invention relates to near field communications (NFC), and more specifically to shaped load modulation in a NFC device.
2. Related Art
Near field communication (NFC) devices are being integrated into mobile devices, such as smartphones for example, to facilitate the use of these mobile devices in conducting daily transactions. For example, instead of carrying numerous credit cards, the credit information provided by these credit cards can be loaded into a NFC device and stored therein to be used as needed. The NFC device is simply tapped to a credit card terminal to relay the credit information to it to complete a transaction. As another example, a ticket writing system, such as those used in bus and train terminals, may simply write ticket fare information onto the NFC device instead of providing a paper ticket to a passenger. The passenger simply taps the NFC device to a reader to ride the bus or the train without the use of the paper ticket.
Conventionally, the credit card information and the ticket fare information are stored onto a NFC device that operates in a target, or tag, mode of operation. This NFC device communicates the information to another NFC device using the information to modulate an impedance across its antenna terminals which is then detected by the other NFC device. This communications scheme is commonly referred to as load modulation. The load modulation should be carefully controlled to prevent introduction of unwanted noise into the communication which may interfere with the communication of the information as well as other communications between other communications devices.
Thus, there is a need to control load modulation in a NFC device that overcomes the shortcomings described above. Further aspects and advantages of the present invention will become apparent from the detailed description that follows.
The present invention will now be described with reference to the accompanying drawings. In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawing in which an element first appears is indicated by the leftmost digit(s) in the reference number.